FORM AND HABIT: THE BILL. 31 



perform tlieir toilet, and, pressing a drop of oil from the 

 gland at the root of the tail, they dress their feathers 

 Avith their liill. Parrots nso the bill in elimhing, and 

 its hawklike shape ia tliese hirds is an umisnal instance 

 of similarity in structure accompanying different hahits. 



Birds ^rliieli do not strike with theii' feet may use 

 the bill as a weapon, but the manner in which it is em- 

 ])loyed corresjjonds so closely with the method by which 

 a bird secures its food, that as a weapon the Ijill pre- 

 sents no special modifications. In constructing the nest 

 the bill may lie used as a trowel, an auger, a needle, a 

 chisel, and as several other tools. 



But as a hand the bill's most important office is tliat 

 of procuring food ; and wonderful indeed are the forms 

 it assmnes to supply the appetites of Ijirds who may 

 re(|uire a drop of nectar or a tiny insect from the heart 

 of a flower, a snake from the marshes, a clam or mussel 

 fr(jm the ocean's beach, or a fish from its ^vaters. The 

 bill, therefore, becomes a forceps, lever, chisel, h(.iok, 

 hammer, a\vl, probe, spoon, s]iear, sieve, net, and knife — 

 in shm-t, there is almost no limit to its shape and uses. 



With Hummingbirds the shape of the lull is appar- 

 ently related to the flowers from which the bird most 

 frecpiently procures its food. It ranges in length from 

 a (piarter of an inch in the 

 Small-ljilled Ilunnner {Micro- 

 rlnjiiclins) to five inches in 

 the 8iphon-bilI {Di>cimaste.i), 

 which has a bill longer than ^ ^ 



. '^ . Fig. 17.— Decurved bill of Siekle- 



itS bijdy, and is said to feed tin Ilumminijljird. ^Natural 



from the long-tubed trumpet 



flowers. The Avocet Hummer (Avocettuhf) has a bill 

 curved slightly upward, but in the Sickle-billed Hummer 

 {Euto:cerp>t) it is curved downward to form half a cii'cle, 

 and the bird feeds on flowers havino- a similarlv curved 



